Analysis of influencing factors on forming limit of GH605 sheet metal

Sheet metal forming limit diagram (FLD) is a comprehensive index used to evaluate sheet metal formability. In this paper, the forming limit curves of GH605 sheet materials with 0.2 mm and 2.5 mm thickness under three different heat treatment conditions were obtained by numerical simulation of bulging. Then, the simulated forming limit results of the three materials with 0.2 mm thickness were compared with the experimental results. The results show that the simulated FLDs can be in good agreement with the experimental FLDs. The influences of work hardening index (n value) and anisotropy index (r value) on the forming limit are analysed from the view of material property difference. The comprehensive simulated and experimental results show that the formability of the sheets after the two kinds of solution treatment is significantly better than that of the annealed sheets. The forming limit curve increases with the increase of n value and r value, and the influence of n value on the forming limit curve is more significant than that of r value. The forming limit diagram established by numerical simulation can provide a theoretical basis for material development and process selection.